Corn Syrup Glycemic Index (GI), Glycemic Load (GL), and Insulin Index (II)
The glycemic index of corn syrup varies depending on its fructose content and added ingredients.
According to The International Tables of Glycemic Index Values, the GI of dark corn syrup from the US is 90±6. Dark corn syrup has a small amount of molasses but no added high-fructose corn syrup (1).
The GI of high-fructose corn syrup has been calculated to be 56, while the GI value for high-fructose corn syrup with added molasses is 50.
Glycemic load values below 55 are considered low, 56 to 69 are medium, and values above 70 are considered high.
The effects of fructose and high-fructose corn syrup on the diabetic profile are still being studied. There is a lack of evidence to suggest they are directly linked to the development of type 2 diabetes at moderate doses. However, there might be a potential cause for concern when fructose is consumed at high doses or contributes excess energy to a diet (2).
To find the complete chart of glycemic index values for over 350 foods, you can visit this page.
Due to its small serving size, corn syrup has a lower glycemic load.
The study mentioned above has calculated the GL of dark corn syrup to be 5 and the GL of high-fructose corn syrup to be 3. However, these values are intended as a general guide and are calculated for the whole food group rather than corn syrup.
We have calculated the glycemic load of dark corn syrup to be 14 for a serving of one tablespoon (20g). The formula used was GL = the GI of the food x available carbohydrates per serving (g) / 100.
A glycemic load value below 10 is considered low, while a GL value in the range of 11 to 19 falls in the medium category.
The insulin index of high-fructose corn syrup was measured to be 65±5. Adding molasses to the syrup lowered its II to 58±5 (3). Corn syrup can be considered to have a medium insulin index value.
To learn more about the insulin index and find a complete chart of insulin index values for over 140 foods, you can visit this page.